- ID:
- ivo://CDS.VizieR/J/A+A/628/A84
- Title:
- Slowly diffusing planetary solutions freq. analysis
- Short Name:
- J/A+A/628/A84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Over short time-intervals, planetary ephemerides have traditionally been represented in analytical form as finite sums of periodic terms or sums of Poisson terms that are periodic terms with polynomial amplitudes. This representation is not well adapted for the evolution of planetary orbits in the solar system over million of years which present drifts in their main frequencies as a result of the chaotic nature of their dynamics. We aim to develop a numerical algorithm for slowly diffusing solutions of a perturbed integrable Hamiltonian system that will apply for the representation of chaotic planetary motions with varying frequencies. By simple analytical considerations, we first argue that it is possible to exactly recover a single varying frequency. Then, a function basis involving time-dependent fundamental frequencies is formulated in a semi-analytical way. Finally, starting from a numerical solution, a recursive algorithm is used to numerically decompose the solution into the significant elements of the function basis. Simple examples show that this algorithm can be used to give compact representations of different types of slowly diffusing solutions. As a test example, we show that this algorithm can be successfully applied to obtain a very compact approximation of the La2004 solution of the orbital motion of the Earth over 40Myr ([-35Myr,5Myr]). This example was chosen because this solution is widely used in the reconstruction of the past climates.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/VI/97
- Title:
- Solar and Lunar Eclipses: 1996-2020
- Short Name:
- VI/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Solar Eclipses - During the twenty-five year period 1996-2020, some portion of the Moon's shadow will sweep across the Earth a total of fifty-six times. Twenty-one of these events result in partial solar eclipses, seventeen of them are annular eclipses, sixteen more are total eclipses and the remaining two are both annular and total along sections of their narrow paths. Local circumstances at the instant of greatest eclipse1 for every event during this quarter century period are presented in solar.dat. The date and Universal Time of the instant of greatest eclipse are found in the first two columns. The eclipse type is given (T=Total, A=Annular, AT=Annular/Total or P=Partial) along with the Saros series, as defined by van den Bergh (1955). The magnitude of the eclipse is defined as the fraction of the Sun's diameter obscured at greatest eclipse. The latitude and longitude of the umbra are given for the instant of greatest eclipse, along with the Sun's altitude, the width of the path (kilometers) and the duration of totality or annularity. For partial eclipses, the latitude and longitude of the point closest to the umbra's axis at the instant of greatest eclipse are listed. The altitude of the Sun at this location is 0 degrees. Note: Greatest eclipse is defined as the instant when the axis of the Moon's shadow passes closest to the Earth's center. For total eclipses, the instant of greatest eclipse is virtually identical to the instants of greatest magnitude and greatest duration. However, for annular eclipses, the instant of greatest duration may occur at either the time of greatest eclipse or near the sunrise and sunset points of the eclipse path. Lunar Eclipses - During the twenty-five year period 1996-2020, the Moon will swing through some portion of Earth's shadow a total of fifty-eight times. Twenty-three of these events result in penumbral lunar eclipses, twelve of them are partial (umbral) eclipses, twenty-three more are total lunar eclipses. Local circumstances at the instant of greatest eclipse1 for every event during this quarter century period are presented in Table 1. The date and Universal Time of the instant of greatest eclipse are found in the first two columns. The eclipse type is given (T=Total, P=Partial [Umbral], or P=Penumbral) along with the Saros series, as defined by van den Bergh (1955). The penumbral and umbral magnitudes of the eclipse are defined as the fraction of the Moon's diameter obscured by either shadow at greatest eclipse. The partial and total semi-durations of the eclipse along with the Greenwich Siderial Time at midnight, and the Moon's Right Ascension and Declination are listed. The start and end times of the partial eclipse can be calculated by respectively subtacting and adding the partial semi-duration (i.e. - Par. SDur) to the instant of greatest eclipse. Likewise, the start and end times of the total eclipse can be calculated by respectively subtacting and adding the total semi-duration (i.e. - Total SDur) to the instant of greatest eclipse. Note: Greatest eclipse is defined as the instant when the Moon passes closest to the axis of Earth's shadow(s). This marks the instant when the Moon is deepest in Earth's shadow(s).
- ID:
- ivo://CDS.VizieR/J/ApJ/787/10
- Title:
- Solar s-process contributions with GCE model
- Short Name:
- J/ApJ/787/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the s-process abundances (A>~90) at the epoch of the solar system formation. Asymptotic giant branch yields are computed with an updated neutron capture network and updated initial solar abundances. We confirm our previous results obtained with a Galactic chemical evolution (GCE) model: (1) as suggested by the s-process spread observed in disk stars and in presolar meteoritic SiC grains, a weighted average of s-process strengths is needed to reproduce the solar s distribution of isotopes with A>130; and (2) an additional contribution (of about 25%) is required in order to represent the solar s-process abundances of isotopes from A=90 to 130. Furthermore, we investigate the effect of different internal structures of the ^13^C pocket, which may affect the efficiency of the ^13^C({alpha},n)^16^O reaction, the major neutron source of the s process. First, keeping the same ^13^C profile adopted so far, we modify by a factor of two the mass involved in the pocket; second, we assume a flat ^13^C profile in the pocket, and we test again the effects of the variation of the mass of the pocket. We find that GCE s predictions at the epoch of the solar system formation marginally depend on the size and shape of the ^13^C pocket once a different weighted range of ^13^C-pocket strengths is assumed. We obtain that, independently of the internal structure of the ^13^C pocket, the missing solar system s-process contribution in the range from A=90 to 130 remains essentially the same.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1247
- Title:
- Solar system survey with Spacewatch
- Short Name:
- J/AJ/133/1247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have completed a low-inclination ecliptic survey for distant and slow-moving bright objects in the outer solar system. This survey used data taken over 34 months by the University of Arizona's Spacewatch Project based at Steward Observatory, Kitt Peak. Spacewatch revisits the same sky area every three to seven nights in order to track cohorts of main-belt asteroids. This survey used a multiple-night detection scheme to extend our rate sensitivity to as low as 0.012"/hr. When combined with our plate scale and flux sensitivity (V~21), this survey was sensitive to Mars-sized objects out to 300AU and Jupiter-sized planets out to 1200AU. The survey covered approximately 8000deg^2^ of raw sky, mostly within 10{deg} of the ecliptic but away from the Galactic center. An automated motion detection program was modified for this multinight search and processed approximately 2 terabytes of imagery into motion candidates. This survey discovered 2003 MW12, currently the tenth largest classical Kuiper Belt object. In addition, several known large Kuiper Belt objects and Centaurs were detected, and the detections were used with a model of our observational biases to make population estimates as a check on our survey efficiency. We found no large objects at low inclinations despite having sufficient sensitivity in both flux and rate to see them out as far as 1200AU. For low inclinations, we can rule out more than one to two Pluto-sized objects out to 100AU and one to two Mars-sized objects to 200AU.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A129
- Title:
- SPHERE (87) Sylvia images
- Short Name:
- J/A+A/650/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dynamical models of Solar System evolution have suggested that the so-called P- and D-type volatile-rich asteroids formed in the outer Solar System beyond Neptune's orbit and may be genetically related to the Jupiter Trojans, comets, and small Kuiper belt objects (KBOs). Indeed, the spectral properties of P- and D-type asteroids resemble that of anhydrous cometary dust. We aim to gain insights into the above classes of bodies by characterizing the internal structure of a large P- and D-type asteroid. We report high-angular-resolution imaging observations of the P-type asteroid (87) Sylvia with the the Very Large Telescope (VLT) Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. These images were used to reconstruct the 3D shape of Sylvia. Our images together with those obtained in the past with large ground-based telescopes were used to study the dynamics of its two satellites. We also modeled Sylvia's thermal evolution. The shape of Sylvia appears flattened and elongated (a/b~1.45; a/c~1.84). We derive a volume-equivalent diameter of 271+/-5km and a low density of 1378+/-45kg/m^3^. The two satellites orbit Sylvia on circular, equatorial orbits. The oblateness of Sylvia should imply a detectable nodal precession which contrasts with the fully-Keplerian dynamics of its two satellites. This reveals an inhomogeneous internal structure, suggesting that Sylvia is differentiated. Sylvia's low density and differentiated interior can be explained by partial melting and mass redistribution through water percolation. The outer shell should be composed of material similar to interplanetary dust particles (IDPs) and the core should be similar to aqueously altered IDPs or carbonaceous chondrite meteorites such as the Tagish Lake meteorite. Numerical simulations of the thermal evolution of Sylvia show that for a body of such a size, partial melting was unavoidable due to the decay of long-lived radionuclides. In addition, we show that bodies as small as 130-150km in diameter should have followed a similar thermal evolution, while smaller objects, such as comets and the KBO Arrokoth, must have remained pristine, which is in agreement with in situ observations of these bodies. NASA Lucy mission target (617) Patroclus (diameter ~140km) may, however, be differentiated.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A132
- Title:
- SPHERE/ZIMPOL (41) Daphne images
- Short Name:
- J/A+A/623/A132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CM-like asteroids (Ch and Cgh classes) are a major population within the broader C-complex, encompassing about 10% of the mass of the main asteroid belt. Their internal structure has been predicted to be homogeneous, based on their compositional similarity as inferred from spectroscopy (Vernazza et al., 2016AJ....152..154G) and numerical modeling of their early thermal evolution (Bland & Travis, 2017, Sci. Adv. 3, e1602514). Here we aim to test this hypothesis by deriving the density of the CM-like asteroid (41) Daphne from detailed modeling of its shape and the orbit of its small satellite. We observed Daphne and its satellite within our imaging survey with the Very Large Telescope extreme adaptive-optics SPHERE/ZIMPOL camera (ID 199.C-0074, PI P. Vernazza) and complemented this data set with earlier Keck/NIRC2 and VLT/NACO observations. We analyzed the dynamics of the satellite with our Genoid meta-heuristic algorithm. Combining our high-angular resolution images with optical lightcurves and stellar occultations, we determine the spin period, orientation, and 3-D shape, using our ADAM shape modeling algorithm. The satellite orbits Daphne on an equatorial, quasi-circular, prograde orbit, like the satellites of many other large main-belt asteroids. The shape model of Daphne reveals several large flat areas that could be large impact craters. The mass determined from this orbit combined with the volume computed from the shape model implies a density for Daphne of 1.77+/-0.26g/cm^3^ (3{sigma}). This density is consistent with a primordial CM-like homogeneous internal structure with some level of macroporosity (~17%). Based on our analysis of the density of Daphne and 75 other Ch/Cgh-type asteroids gathered from the literature, we conclude that the primordial internal structure of the CM parent bodies was homogeneous.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A154
- Title:
- SPHERE/ZIMPOL (89) Julia images
- Short Name:
- J/A+A/618/A154
- Date:
- 23 Mar 2022 16:27:22
- Publisher:
- CDS
- Description:
- The vast majority of the geophysical and geological constraints (e.g., internal structure, cratering history) for main-belt asteroids have so far been obtained via dedicated interplanetary missions (e.g., ESA Rosetta, NASA Dawn). The high angular resolution of SPHERE/ZIMPOL, the new-generation visible adaptive-optics camera at ESO VLT, implies that these science objectives can now be investigated from the ground for a large fraction of D>=100km main-belt asteroids. The sharp images acquired by this instrument can be used to accurately constrain the shape and thus volume of these bodies (hence density when combined with mass estimates) and to characterize the distribution and topography of D>=30km craters across their surfaces. Here, via several complementary approaches, we evaluated the recently proposed hypothesis that the S-type asteroid (89) Julia is the parent body of a small compact asteroid family that formed via a cratering collisional event. We observed (89) Julia with VLT/SPHERE/ZIMPOL throughout its rotation, derived its 3D shape, and performed a reconnaissance and characterization of the largest craters. We also performed numerical simulations to first confirm the existence of the Julia family and to determine its age and the size of the impact crater at its origin. Finally, we utilized the images/3D shape in an attempt to identify the origin location of the small collisional family. On the one hand, our VLT/SPHERE observations reveal the presence of a large crater (D~75km) in Julia's southern hemisphere. On the other hand, our numerical simulations suggest that (89) Julia was impacted 30-120Myrs ago by a D~8km asteroid, thereby creating a D>=60km impact crater at the surface of Julia. Given the small size of the impactor, the obliquity of Julia and the particular orientation of the family in the (a,i) space, the imaged impact crater is likely to be the origin of the family. New doors into ground-based asteroid exploration, namely, geophysics and geology, are being opened thanks to the unique capabilities of VLT/SPHERE. Also, the present work may represent the beginning of a new era of asteroid-family studies. In the fields of geophysics, geology, and asteroid family studies, the future will only get brighter with the forthcoming arrival of 30-40m class telescopes like ELT, TMT, and GMT.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/3267
- Title:
- Stellar encounters with long-period comets
- Short Name:
- J/MNRAS/454/3267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Solar system's Oort cloud can be perturbed by the Galactic tide and by individual passing stars. These perturbations can inject Oort cloud objects into the inner parts of the Solar system, where they may be observed as the long-period comets (periods longer than 200yr). Using dynamical simulations of the Oort cloud under the perturbing effects of the tide and 61 known stellar encounters, we investigate the link between long-period comets and encounters. We find that past encounters were responsible for injecting at least 5 percent of the currently known long-period comets. This is a lower limit due to the incompleteness of known encounters. Although the Galactic tide seems to play the dominant role in producing the observed long-period comets, the non-uniform longitude distribution of the cometary perihelia suggests the existence of strong - but as yet unidentified - stellar encounters or other impulses. The strongest individual future and past encounters are probably HIP 89825 (Gliese 710) and HIP 14473, which contribute at most 8 and 6 percent to the total flux of long-period comets, respectively. Our results show that the strength of an encounter can be approximated well by a simple proxy, which will be convenient for quickly identifying significant encounters in large data sets. Our analysis also indicates a smaller population of the Oort cloud than is usually assumed, which would bring the mass of the solar nebula into line with planet formation theories.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A25
- Title:
- Sulamitis and Clarissa asteroids spectra
- Short Name:
- J/A+A/610/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The low-inclination (i<80{deg}) primitive asteroid families in the inner main belt, that is, Polana-Eulalia, Erigone, Sulamitis, and Clarissa, are considered to be the most likely sources of near-Earth asteroids (101955) Bennu and (162173) Ryugu. These two primitive NEAs will be visited by NASA OSIRIS-REx and JAXA Hayabusa 2 missions, respectively, with the aim of collecting samples of material from their surfaces and returning them back to Earth. In this context, the Primitive Asteroid Spectroscopic Survey (PRIMASS) was born, with the main aim to characterize the possible origins of these NEAs and constrain their dynamical evolution. As part of the PRIMASS survey we have already studied the Polana and Erigone collisional families in previously published works. The main goal of the work presented here is to compositionally characterize the Sulamitis and Clarissa families using visible spectroscopy. We have observed 97 asteroids (64 from Sulamitis and 33 from Clarissa) with the OSIRIS instrument (0.5-0.9um) at the 10.4m Gran Telescopio Canarias (GTC). We found that about 60% of the sampled asteroids from the Sulamitis family show signs of aqueous alteration on their surfaces. We also found that the majority of the Clarissa members present no signs of hydration. The results obtained here show similarities between Sulamitis-Erigone, and Clarissa-Polana collisional families.
- ID:
- ivo://CDS.VizieR/J/MNRAS/403/1089
- Title:
- SUNS and DEBRIS surveys target selection
- Short Name:
- J/MNRAS/403/1089
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Debris discs - analogous to the asteroid and Kuiper-Edgeworth belts in the Solar system - have so far mostly been identified and studied in thermal emission shortward of 100um. The Herschel space observatory and the Submillimetre Common-User Bolometer Array-2 (SCUBA-2) camera on the James Clerk Maxwell Telescope will allow efficient photometric surveying at 70 to 850um, which allows for the detection of cooler discs not yet discovered, and the measurement of disc masses and temperatures when combined with shorter wavelength photometry. The SCUBA-2 Unbiased Nearby Stars survey (SUNS) and the Disc Emission via a Bias-free Reconnaissance in the Infrared/Submillimetre (DEBRIS) Herschel Open Time Key Project are complementary legacy surveys observing samples of ~500 nearby stellar systems. To maximize the legacy value of these surveys, great care has gone into the target selection process. This paper describes the target selection process and presents the target lists of these two surveys.
